What is the maximum rise for deck stairs in Ontario?

Exterior stairs serving a house are private stairs, so each rise must be between 125 mm and 200 mm, and the run of rectangular treads between 255 mm and 355 mm (Division B, Table 9.8.4.1.).

How wide do deck stairs have to be?

Exterior stairs serving a single dwelling unit must be at least 860 mm wide (Division B, Sentence 9.8.2.1.(4)). Handrails and stringers may project not more than 100 mm into that width (Article 9.8.7.6.).

Do deck stairs need a guard?

Yes, on any open side where the drop to the surface within 1.2 m is more than 600 mm (Division B, Sentence 9.8.8.1.(1)). For a house, the guard is at least 900 mm high where the stair is not more than 1,800 mm above finished ground, measured from a line through the nosings (Article 9.8.8.3.).

Is a landing needed at the bottom of deck stairs?

A landing is required at the top and bottom of each flight, but finished ground sloping not more than 1 in 50 counts as a landing. The bottom landing may be omitted where no gate or door obstructs the area within the lesser of the stair width or 900 mm (Division B, Articles 9.8.6.1. and 9.8.6.2.).

How far apart can deck stair stringers be?

For stairs serving one dwelling unit, wood stringers may be spaced not more than 900 mm on centre, or 1,200 mm where risers support the front of the treads. Each stringer needs at least 90 mm effective depth and 235 mm overall depth (Division B, Article 9.8.9.4.).

Deck Stairs Ontario: Rise, Run and Handrails (2024 Code)

Q: Do deck stairs need a handrail in Ontario?

Exterior stairs serving one dwelling unit need no handrail with not more than 3 risers. With more than 3 risers, one handrail is enough for stairs serving not more than one dwelling unit or a house with a secondary suite (Division B, Sentences 9.8.7.1.(3) and (4)).

Last updated October 24, 2026

Deck stairs serving a house in Ontario are "private stairs" under the 2024 Building Code, so each rise must be 125 mm to 200 mm and each run 255 mm to 355 mm (OBC Div. B Table 9.8.4.1.). The stair must be at least 860 mm wide (OBC Div. B 9.8.2.1.) and needs one handrail once it has more than 3 risers (OBC Div. B 9.8.7.1.). Guards are a separate requirement, triggered by a drop of more than 600 mm.

This page applies the general stair rules in Section 9.8 to the exterior stairs of a deck serving one house, or a house with a secondary suite. Exterior stairs serving more than one dwelling unit, other than a house with a secondary suite, are public stairs with stricter limits. Check with your building department, since permits and local requirements apply to deck stairs too.

Deck stair values at a glance

Item	Deck stair serving a house	Article
Rise	125 mm to 200 mm	Table 9.8.4.1.
Run (rectangular treads)	255 mm to 355 mm	Table 9.8.4.1.
Tread depth	run to run + 25 mm	9.8.4.2.(2)
Riser tolerance	5 mm adjacent, 10 mm in a flight	9.8.4.4.
Width	860 mm	9.8.2.1.(4)
Headroom	1,950 mm	9.8.2.2.(3)
Max height of one flight	3.7 m	9.8.3.3.
Handrail	none up to 3 risers; one above 3	9.8.7.1.(3), (4)
Handrail height	865 mm to 1,070 mm	9.8.7.4.
Guard	where the drop exceeds 600 mm	9.8.8.1.
Guard height	900 mm, or 1,070 mm above 1,800 mm	9.8.8.3.
Stringer spacing	900 mm o.c. (1,200 mm with supporting risers)	9.8.9.4.

This is our own summary. Read the articles before you cut stringers.

Rise, run and tread depth

Rise is the vertical distance from nosing to nosing (9.8.4.1.). The note to Table 9.8.4.1. defines private stairs to include exterior stairs serving a house with a secondary suite or an individual dwelling unit, so a deck stair gets the private limits: rise 125 mm to 200 mm, run 255 mm to 355 mm. The tread itself must be at least as deep as the run and not more than the run plus 25 mm (9.8.4.2.).

Steps must be uniform. Adjacent risers may differ by not more than 5 mm, and the tallest and shortest riser in a flight by not more than 10 mm, with the same tolerances for runs (9.8.4.4.). Where the bottom riser meets a sloping surface such as a driveway or walk, its height may vary across the stair by up to 1 in 12. Treads may slope no more than 1 in 50.

Open risers are permitted on exterior stairs serving a single dwelling unit or a house with a secondary suite (9.8.4.9.). Nosings need a rounded or bevelled edge of 6 mm to 14 mm (9.8.4.8.).

Quick layout check. A deck surface 1,100 mm above the landing pad, divided into 6 risers, gives about 183 mm per riser, inside the 200 mm limit. Five risers would give 220 mm, which is too steep. With 6 risers you have 5 treads, each with a run of at least 255 mm.

Width, headroom and flight height

Exterior stairs serving a single dwelling unit, other than required exit stairs, must be at least 860 mm wide, and exit stairs serving a house also need 860 mm (9.8.2.1.). Handrails, their supports and stringers may not project more than 100 mm into that required width (9.8.7.6.), so plan the clear width between stringers or posts with that in mind.

Headroom for stairs serving a house is 1,950 mm, measured from a line tangent to the nosings (9.8.2.2.). This matters for stairs that run under an upper deck or a beam.

No single flight may rise more than 3.7 m (9.8.3.3.). A stair from a high second-storey deck may need an intermediate landing to stay within that limit.

Landings

A landing is required at the top and bottom of each flight, and where a doorway opens onto a stair (9.8.6.2.(1)). For deck stairs, the useful points are:

What counts as a landing. Finished floors, and ground surfaces sloping not more than 1 in 50, at the top and bottom of a stair are considered landings (9.8.6.1.(3)). In practice that is usually the deck surface at the top and a level pad or patio at the bottom.
Bottom landing. It may be omitted where there is no obstruction, such as a gate or door, within the lesser of the stair width or 900 mm for a stair serving a single dwelling unit (9.8.6.2.(4)).
Short stairs at a secondary entrance. The top landing may be omitted for an exterior flight of not more than 3 risers at a secondary entrance, where the main door slides or swings away and only a storm or screen door with a hold-open swings over the stair (9.8.6.2.(3)).
Size. A landing is at least as wide and as long as the stair width. A straight-through landing need not be longer than the required width or 1,100 mm, whichever is less, and landings may slope no more than 1 in 50 (9.8.6.3.). Headroom over a house landing is 1,950 mm (9.8.6.4.).

Handrails

Exterior stairs serving a single dwelling unit need no handrail if they have not more than 3 risers. With more than 3 risers, one handrail is enough for stairs serving not more than one dwelling unit or a house with a secondary suite (9.8.7.1.(3) and (4)). See handrail height in Ontario for the full rules.

Height. 865 mm to 1,070 mm, measured to a line tangent to the nosings (9.8.7.4.).
Length. Continuously graspable from the bottom riser to the top riser. For a house, the handrail may start from a newel post or volute on the bottom tread (9.8.7.2.), and the 300 mm horizontal extensions at top and bottom are not required (9.8.7.3.(2)).
Grip and clearance. At least 50 mm clear of the surface behind, or 60 mm if that surface is rough, with nothing on the rail that breaks a handhold (9.8.7.5.).
Strength. A handrail must resist a 0.9 kN concentrated load. For a house, attachment to wood studs or blocking is deemed to comply with points not more than 1.2 m apart, the first within 300 mm of each end, and at least two No. 8 wood screws per point, 32 mm into solid wood (9.8.7.7.).

Guards on deck stairs

A guard is required on each open side of a flight of steps where the drop to the surface within 1.2 m is more than 600 mm (9.8.8.1.(1)). On a long deck stair, the lower treads often fall below that trigger while the upper ones do not.

Height. An exterior guard serving one dwelling unit is at least 900 mm high where the walking surface is not more than 1,800 mm above finished ground, and 1,070 mm above that. On stairs, the height is measured from a line through the tread nosings (9.8.8.3.).
Openings. Must stop a 100 mm sphere, and the triangle formed by the riser, tread and bottom rail must stop a 150 mm sphere (9.8.8.5.).
Climbing. No member or opening between 140 mm and 900 mm above the walking surface may make the guard easy to climb (9.8.8.6.).
SB-7. Guards built to Supplementary Standard SB-7 are deemed to meet the guard load requirements (9.8.8.2.(6)). Exterior guards follow Section 2 of SB-7 (SB-7 1.1.1.). SB-7's stair guard table is in Section 3, which is for interior guards (SB-7 3.2.3.), so ask your building department how it wants an exterior stair guard detailed.

The deck railing itself is covered in deck railing height in Ontario.

Stringers, treads and footings

Design load. Stairs serving one dwelling unit are designed for 1.9 kPa (9.8.9.1.).
Stringers. Wood stringers need an effective depth of at least 90 mm at the narrowest point and an overall depth of at least 235 mm. They must be supported and secured top and bottom, be at least 38 mm thick if unsupported along their length (25 mm if supported), and be spaced not more than 900 mm on centre, or 1,200 mm where risers support the front of the treads (9.8.9.4.).
Ground contact. Exterior wood steps may not touch the ground unless treated with a wood preservative (9.8.9.3.). Structural wood less than 150 mm above finished ground must be pressure-treated (9.3.2.9.(3)).
Concrete steps. Exterior concrete steps with 1 or 2 risers may be laid on the ground; steps with more than 2 risers need foundations to the depths required by 9.12.2.2. (9.12.2.2.(3) and (4)) and must sit on walls or piers at least 150 mm in cross-section or be cantilevered from the foundation wall (9.8.9.2.).

Common mistakes

Dividing the total rise without checking the 200 mm limit, or measuring before the landing pad is placed.
Uneven bottom riser after a pad or paving stone is added.
Clear width under 860 mm once stringers and a handrail are installed.
No handrail on a 4-riser stair because the builder counted treads instead of risers.
Guard measured from the tread instead of the nosing line.
Untreated stringers resting on soil.

How to look it up yourself

In the 2024 Compendium, open Division B, Part 9, Section 9.8. Search for:

"Private stairs" (Table 9.8.4.1. notes)
"exterior stairs serving a single dwelling unit" (width and handrails)
"Required Landings"
"Wooden Stair Stringers"
"line drawn through the tread nosing" (guard height on stairs)

Stairs, handrails and guards (Section 9.8) are on the House exam syllabus. Read the free House exam study guide and try the free practice quiz on that page.

Based on the official 2024 Building Code Compendium on ontario.ca.

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Deck Stairs in Ontario: Rise, Run, Handrails and Guards

Deck stair values at a glance

Rise, run and tread depth

Width, headroom and flight height

Landings

Handrails

Guards on deck stairs

Stringers, treads and footings

Common mistakes

How to look it up yourself

Sources

Start practising for your BCIN exam, free

Frequently asked questions

Deck Stairs in Ontario: Rise, Run, Handrails and Guards

Deck stair values at a glance

Rise, run and tread depth

Width, headroom and flight height

Landings

Handrails

Guards on deck stairs

Stringers, treads and footings

Common mistakes

How to look it up yourself

Related pages

Sources

Start practising for your BCIN exam, free

Frequently asked questions